Receptorcargo

Receptorcargo is a term used in cell biology to describe the functional unit formed when a cell-surface receptor binds to its cargo and initiates intracellular trafficking. It refers not only to the receptor itself but also to the cargo and the trafficking machinery that recognize the complex and determine its fate inside the cell.

Mechanistically, receptorcargo is often taken up by receptor-mediated endocytosis, frequently via clathrin-coated pits. Cargoes present sorting signals recognized by adaptor proteins such as AP-2, enabling clathrin assembly and vesicle formation. After internalization, the receptor–cargo complex reaches early endosomes, where changes in pH can trigger cargo release or receptor recycling. Sorting decisions in late endosomes and lysosomes determine whether the receptor is recycled to the plasma membrane or directed toward degradation; some cargoes are routed to specific organelles or across cells by transcytosis. Ubiquitination of receptors or cargo and the action of Rab GTPases and tethering factors further guide these routes.

Examples include the LDL receptor carrying low-density lipoprotein particles, the transferrin receptor carrying transferrin-bound iron, and the mannose-6-phosphate receptor delivering lysosomal enzymes. Not all receptor interactions with ligands are limited to signaling; the term receptorcargo emphasizes the endocytic fate and intracellular trafficking of the internalized complex.

Understanding receptorcargo trafficking is important for physiology and disease, as defects in sorting can lead to altered cargo accumulation or impaired receptor recycling, influencing cholesterol homeostasis, iron uptake, or receptor sensitivity in disease states. See also receptor-mediated endocytosis and cargo sorting.